Please download the example capx and set an event for the "every tick" condition like shown below.
<img src="http://dl.dropbox.com/u/3138530/bug.jpg" border="0">
Afterwards save and close the project. The event will be absent when you load it back. I think it only happens when the instance variable in question is a boolean.
This is discovered in this thread.
I'm using Windows 7 x64